The present invention relates to a repair fuse circuit and, more particularly, to a repair fuse circuit for storing Input/Output (I/O) repair information, which can reduce the number of fuses.
In general, in a semiconductor circuit, I/O information, which will be repaired within a redundant block, is controlled using a fuse. As a chip generally operates in x8 and x16, four I/O fuse boxes are required in a repair line. Two fuses for low and high are used in one repair box.
FIG. 1 is a circuit diagram of a conventional repair fuse circuit.
A repair fuse circuit 100 includes an inverter 1100, a fuse unit F100, and a plurality of the transfer gates T110 to T140. The inverter 1100 inverts an external repair signal REP and outputs inverted repair signal IREP. The fuse unit F100 includes first to fourth fuse blocks FB110 to FB140. Each of the fuse blocks FB110 to FB140 includes a first fuse Fa connected to an input terminal to which the repair signals REP is input, and a second fuse Fb connected to a ground terminal.
Furthermore, each of the fuse blocks FB110 to FB140 outputs a logic high or a logic low depending on the open/closed state of the first and second fuses Fa, Fb with the repair signals REP. The first to fourth transfer gates T110 to T140 are turned on or off in response to the repair signal REP and the inverted repair signal IREP, and output logic signals, which are output from the first to fourth fuse blocks FB110 to FB140 to external I/O buses I/OBUS<0:3>.
The operation of the conventional redundancy I/O fuse circuit constructed above is as follows. The first or second fuses Fa, Fb within the first to fourth fuse blocks FB 110 to FB 140 is cut (or blown) through a specific test. For example, if I/O<9> is to be repaired, the second fuse Fb of each of the first and fourth fuse blocks FB 110 and FB 140 is cut (or open), and the first fuse Fa of each of the second and third fuse blocks FB 120 and FB 130 is open. Consequently, a logic signal ‘1001’ is output through the I/O bus I/OBUS<0:3>, and a repair multiplexer (not shown) replaces a main data line, corresponding to I/O<9> with a redundancy data line according to the logic signal ‘1001’.
As in the above, in order to represent I/O repair information, the fuse unit F100 including eight or more fuses is required. The fuse unit F100 is used as many times as the number of repair columns. Further, in order to synchronize logic signal output from the fuse blocks FB110 to FB140 and to transfer them to the respective I/O buses I/OBUS<0:3>; it requires four transfer gates T110 to T140 including one PMOS transistor and one NMOS transistor. When the number of repair columns is 32, 256 fuses, corresponding to fuse number (8)*repair column number (32), are required.